Is there a way to get icon_value for the UIList using icon name from enum?
Look at the icons addon.
If you look at the code to the Development Icons Addon will see that it uses data defined in that very UILayout.icon  development_icon_get.py Line 86 in version 1.4 method mentioned in question.
Which if crunched into python console
&gt;&gt;&gt; icons = bpy.types.UILayout.bl_rna.functions[
...                 &quot;prop&quot;].parameters[&quot;icon&quot;].enum_items.keys()

&gt;&gt;&gt; 
&gt;&gt;&gt; icons
['NONE', 'QUESTION', 'ERROR', 'CANCEL', 'TRIA_RIGHT', 'TRIA_DOWN', 'TRIA_LEFT', 'TRIA_UP', ...

There are over 800
&gt;&gt;&gt; len(icons)
802

Make a reverse lookup, name -&gt; index
&gt;&gt;&gt; icon_ref = {k : i for i, k in enumerate(icons)}
&gt;&gt;&gt; icon_ref['XRAY']
563

Or using items()
&gt;&gt;&gt; icons = bpy.types.UILayout.bl_rna.functions[
...                 &quot;prop&quot;].parameters[&quot;icon&quot;].enum_items.items()
&gt;&gt;&gt; icons[100]
('IMAGE', &lt;bpy_struct, EnumPropertyItem(&quot;IMAGE&quot;) at 0xbb1c6c0&gt;)